Post-Saccadic Oscillations of the Pupil and Lens Reduce Fixation Stability in Retinitis Pigmentosa and Age-Related Macular Degeneration.

Purpose: Post-saccadic oscillations (PSOs) reflect movements of gaze that result from motion of the pupil and lens relative to the eyeball rather than eyeball rotations. Here, we analyzed the characteristics of PSOs in subjects with age-related macular degeneration (AMD), retinitis pigmentosa (RP), and normal vision (NV). Our aim was to assess the differences in PSOs between people with vision loss and healthy controls because PSOs affect retinal image stability after each saccade. Methods: Participants completed a horizontal saccade task and their gaze was measured using a pupil-based eye tracker. Oscillations occurring in the 80 to 200 ms post-saccadic period were described with a damped oscillation model. We compared the amplitude, decay time constant, and frequency of the PSOs for the three different groups. We also examined the correlation between these PSO parameters and the amplitude, peak velocity, and final deceleration of the preceding saccades. Results: Subjects with vision loss (AMD, n = 6, and RP, n = 5) had larger oscillation amplitudes, longer decay constants, and lower frequencies than subjects with NV (n = 7). The oscillation amplitudes increased with increases in saccade deceleration in all three groups. The other PSO parameters, however, did not show consistent correlations with either saccade amplitude or peak velocity. Conclusions: Post-saccadic fixation stability in AMD and RP is reduced due to abnormal PSOs. The differences with respect to NV are not due to differences in saccade kinematics, suggesting that anatomic and neuronal variations affect the suspension of the iris and the lens in the patients' eyes.

The long and short of it: a comprehensive assessment of axial length estimation in myopic eyes from ocular and demographic variables.

BACKGROUND/OBJECTIVES: Axial length, a key measurement in myopia management, is not accessible in many settings. We aimed to develop and assess machine learning models to estimate the axial length of young myopic eyes. SUBJECTS/METHODS: Linear regression, symbolic regression, gradient boosting and multilayer perceptron models were developed using age, sex, cycloplegic spherical equivalent refraction (SER) and corneal curvature. Training data were from 8135 (28% myopic) children and adolescents from Ireland, Northern Ireland and China. Model performance was tested on an additional 300 myopic individuals using traditional metrics alongside the estimated axial length vs age relationship. Linear regression and receiver operator characteristics (ROC) curves were used for statistical analysis. The contribution of the effective crystalline lens power to error in axial length estimation was calculated to define the latter's physiological limits. RESULTS: Axial length estimation models were applicable across all testing regions (p ≥ 0.96 for training by testing region interaction). The linear regression model performed best based on agreement metrics (mean absolute error [MAE] = 0.31 mm, coefficient of repeatability = 0.79 mm) and a smooth, monotonic estimated axial length vs age relationship. This model was better at identifying high-risk eyes (axial length >98th centile) than SER alone (area under the curve 0.89 vs 0.79, respectively). Without knowing lens power, the calculated limits of axial length estimation were 0.30 mm for MAE and 0.75 mm for coefficient of repeatability. CONCLUSIONS: In myopic eyes, we demonstrated superior axial length estimation with a linear regression model utilising age, sex and refractive metrics and showed its clinical utility as a risk stratification tool.

Examining the Validity of a New Method for the Objective Assessment of Binocular Accommodative Facility (2Q-AF Test): A Comparison with ± 2.00 DS Lens Flippers.

PURPOSE: Recent technological advances have permitted to objectively record the accommodative response while shifting between two different levels of accommodation. This study is aimed at examining the concurrent validity of a new objective method for the qualitative and quantitative assessment of binocular accommodative facility, which is named 2Q-AF test, in comparison to the ±2.00 DS lens flippers. METHODS: Fifty-six individuals took part in this study (36 healthy young adults [24.4 ± 3.2 years] and 20 children [12.2 ± 0.4 years]). Participants randomly performed the 2Q-AF and the ±2.00 DS lens flipper tests. For the 2Q-AF test, a binocular open-field autorefractor was used to record the magnitude of accommodative response during a 60-sec period, while participants repeatedly changed fixation from a 5 m to a 40 cm chart when clarity of vision was achieved at each level. Due to the advantages of the proposed method, we have determined the number of cycles and the 2Q-AF score, with the latter also considering the accuracy of changes in accommodation. A standard procedure was followed for the ±2.00 DS flipper test. RESULTS: Our data exhibited a moderate association between the number of cycles with the ±2.00 DS lens flippers and the number of cycles in the 2Q-AF test in the group of young adults (p = .005, r = 0.46 [0.15-0.68]) and children (p = .007, r = 0.58 [0.19-0.81]), whereas a stronger relationship was observed when considering the number of cycles with the ±2.00 DS lens flippers and the 2Q-AF score (young adults: p < .001, r = 0.83 [0.69-0.91]; and children: p < .001, r = 0.78 [0.52-0.91]). CONCLUSIONS: The current findings show that the 2Q-AF test is a valid method for accommodative facility assessment, as suggested by its good levels of reliability and validity. This method allows to examine the accommodative facility in qualitative terms and solve most of the limitations associated with the ±2.00 DS lens flipper test.

Age-related changes of lens stiffness in wild-type and Cx46 knockout mice.

We have investigated how connexin 46 (Cx46) regulates lens stiffness by studying different Cx46 knockout (Cx46KO) mice. A modified muscle lever system was used to determine the lens stiffness of wild-type (WT) and Cx46KO mice at the C57BL/6J (B6) and the 129SvJae (129) strain backgrounds according to total lens displacement at the point of maximum force when fresh lenses were compressed with a maximum of 2 mN of force. In comparison to B6-WT controls, young and old B6-Cx46KO lenses showed 23% and 28% reductions in lens displacement, respectively. Comparing to 129-WT controls, old 129-Cx46KO lenses showed 50% reduction in the lens displacement while young 129-Cx46KO lenses displayed similar displacement. Old B6-Cx46KO and old 129-Cx46KO lenses showed almost identical lens displacement, 128 µm versus 127 µm. Morphological data revealed unique changes of peripheral fiber cell shapes in young B6-WT lenses but not in young B6-Cx46KO, 129-WT and 129-Cx46KO lenses. This work reveals Cx46 deletion increases the lens stiffness in both young and old mice at B6 strain background but only in old mice at 129 strain background which contains intermediate filament CP49 gene deletion. Cx46 impairment increases old mouse lens stiffness and may contribute to the development of presbyopia.

Deletion of beaded filament proteins or the C-terminal end of Aquaporin 0 causes analogous abnormal distortion aberrations in mouse lens.

Lens-specific beaded filament (BF) proteins CP49 and filensin interact with the C-terminus of the water channel protein Aquaporin 0 (AQP0). Previously we have reported that a C-terminally end-deleted AQP0-expressing transgenic mouse model AQP0ΔC/ΔC developed abnormal optical aberrations in the lens. This investigation was undertaken to find out whether the total loss of the BF structural proteins alter the optical properties of the lens and cause optical aberrations similar to those in AQP0ΔC/ΔC lenses; also, to map the changes in the optical quality as a function of age in the single or double BF protein knockouts as well as to assess whether there is any significant change in the water channel function of AQP0 in these knockouts. A double knockout mouse (2xKO) model for CP49 and filensin was developed by crossing CP49-KO and filensin-KO mice. Wild type, CP49-KO, filensin-KO, and 2xKO lenses at different ages, and AQP0ΔC/ΔC lenses at postnatal day-17 were imaged through the optical axis and compared for optical quality and focusing property. All three knockout models showed loss of transparency, and development of abnormal optical distortion aberration similar to that in AQP0ΔC/ΔC. Copper grid focusing by the lenses at 6, 9 and 12 months of age showed an increase in aberrations as age advanced. With progression in age, the grid images produced by the lenses of all KO models showed a transition from a positive barrel distortion aberration to a pincushion distortion aberration with the formation of three distinct aberration zones similar to those produced by AQP0ΔC/ΔC lenses. Water permeability of fiber cell membrane vesicles prepared from CP49-KO, filensin-KO and 2xKO models, measured using the osmotic shrinking method, remained similar to that of the wild type without any statistically significant alteration (P > 0.05). Western blotting and quantification revealed the expression of comparable quantities of AQP0 in all three BF protein KOs. Our study reveals that loss of single or both beaded filament proteins significantly affect lens refractive index gradient, transparency and focusing ability in an age-dependent manner and the interaction of BF proteins with AQP0 is critical for the proper functioning of the lens. The presence of BF proteins is necessary to prevent abnormal optical aberrations and maintain homeostasis in the aging lens.

Prediction accuracy of conventional and total keratometry for intraocular lens power calculation in femtosecond laser-assisted cataract surgery.

This study evaluated the accuracy of total keratometry (TK) and standard keratometry (K) for intraocular lens (IOL) power calculation in eyes treated with femtosecond laser-assisted cataract surgery. The retrospective study included a retrospective analysis of data from 62 patients (91 eyes) who underwent uneventful femtosecond laser-assisted cataract surgery with Artis PL E (Cristalens Industrie, Lannion, France) IOL implantation by a single surgeon between May 2020 and December 2020 in Severance Hospital, Seoul, South Korea. The new IOLMaster 700 biometry device (Carl Zeiss Meditec, Jena, Germany) was used to calculate TK and K. The mean absolute error (MAE), median absolute error (MedAE), and the percentages of eyes within prediction errors of ± 0.25 D, ± 0.50 D, and ± 1.00 D were calculated for all IOL formulas (SRK/T, Hoffer-Q, Haigis, Holladay 1, Holladay 2, and Barrett Universal II). There was strong agreement between K and TK (intraclass correlation coefficient = 0.99), with a mean difference of 0.04 D. For all formulas, MAE tended to be lower for TK than for K, and relatively lower MAE and MedAE values were observed for SRK/T and Holladay 1. Furthermore, for all formulas, a greater proportion of eyes fell within ± 0.25 D of the predicted postoperative spherical equivalent range in the TK group than in the K group. However, differences in MAEs, MedAEs, and percentages of eyes within the above prediction errors were not statistically significant. In conclusion, TK and K exhibit comparable performance for refractive prediction in eyes undergoing femtosecond laser-assisted cataract surgery.

Estimating principal plane positions for ocular power calculations in children and adults.

PURPOSE: To develop an age-dependent model to estimate the positions of the ocular and lenticular principal planes (pps) for use in ocular and axial power calculations. METHODS: Ocular power of the eye (Peye ) and axial power (Pax ) were calculated based on previously published average data of the ocular biometry and refraction in newborn infants, children and adults, as well as the associated pp positions. Next, regressions of the pp positions were made as a function of the logarithm of age, which were subsequently used to estimate Peye and Pax . These regression-based estimates were compared with the original data for validation. Finally, this procedure was repeated using the Atchison myopic eye model to determine the influence of myopia on the regression estimates. RESULTS: In adults, the corneal pps almost coincide at 0.058 mm in front of the cornea. The first lenticular pp position relative to the corneal apex is described by the equation: 5.809 - 0.697·exp(-0.211·Age) (r2  = 0.96), and the second lenticular pp by 6.026 - 0.684·exp(-0.232·Age) (r2  = 0.95). The first ocular pp position relative to the corneal apex is at 0.293·exp(-0.232·Age) - 2.2·10-3 ·Age + 1.723 (r2  = 0.99) and the second ocular pp is located at 0.392·exp(-0.181·Age) - 2.4·10-3 ·Age + 2.093 (r2  = 0.99). Estimates of Peye and Pax derived from these regressions led to minor differences from the original values (0.00 ± 0.06D and 0.00 ± 0.10D, respectively). These errors were not affected by ocular refraction between -10D and 0D, with errors of + 0.12 ± 0.00D and -0.02 ± 0.05D for Peye and Pax , respectively. CONCLUSION: The proposed regression models of the pp positions are sufficiently accurate to estimate Peye and Pax reliably. Interestingly, although the adult lens undergoes considerable physiological changes, its pps remain fixed with respect to the corneal apex.

Crystalline Lens Power and Associated Factors in Highly Myopic Children and Adolescents Aged 4 to 19 Years.

PURPOSE: To investigate the distribution characteristics of lens power in highly myopic Chinese children and adolescents and its association with age, axial length (AL), and spherical equivalent (SE). DESIGN: Cross-sectional study. METHODS: A total of 459 highly myopic (SE ≤-5 diopter [D]) children and adolescents aged 4-19 years were included in the study. Participants underwent a series of ophthalmic examinations, which included AL, cycloplegic refraction, and Pentacam measurements. Lens power was calculated using Bennett's formula with its distribution described by age, AL, and SE. Multiple regression was conducted to analyze the associated factors of lens power. RESULTS: Greater lens power was independently associated with younger age, girls, shorter AL, and thicker lens thickness (standardized ß = -0.203, 0.214, -0.379 and 0.492, respectively; all P < .001). However, a significant difference in lens power with age was only found in participants younger than 9 years, after which it reached a plateau (mean difference of 1.23 and 0.084 D per age group, respectively). Lens power was negatively associated with AL only in participants with AL <27 mm. No correlation was observed between lens power and SE. CONCLUSION: Among highly myopic children and adolescents, differences in lens power with age declined significantly after 9 years of age, which was 1 year earlier than non-high myopic patients in previous studies, which implied differences in pathophysiological process between non-high myopia and high myopia. The decoupling of lens power and AL in eyes >27 mm might represent the limited influence of AL on lens power.

Prevalence and risk factors for age-related cataract in Sweden.

BACKGROUND: Cataract is a major cause of visual impairment worldwide. There is a paucity of prevalence studies from Sweden. Therefore, we report the prevalence of cataract and its risk factors in a population-based study of older adults in Sweden. METHODS: The Tierp Glaucoma Survey was conducted in the municipality of Tierp, Sweden, including 760 subjects aged 65-74 years. The presence of cataract was determined based on retroillumination, with lens opacities evident on slit-lamp examination. To assess risk factors for cataract, odds ratios (ORs) were calculated, adjusted for age and gender. RESULTS: A total of 234 individuals were found to have cataract, 12 of whom had undergone cataract surgery. The prevalence adjusted for nonparticipation was 31.5% (95% confidence interval [CI] 29.4-33.6), 35.2% (95% CI 28.7-41.8) in females and 26.2% (95% CI 19.8-32.6) in males. Cataract was associated with age ≥70 years (OR 1.93; 95% CI 1.41-2.64), female gender (OR 1.54; 95% CI 1.12-2.11), and myopia (OR 2.3; 95% CI 1.16-3.56), while pseudoexfoliation, smoking, diabetes, hypertension, and ischaemic heart disease were not. CONCLUSION: Nearly one-third of the sample were estimated to have lens opacities, or had undergone cataract surgery, making cataract a frequent disorder of older age. The study provided further evidence that increasing age, female gender, and myopia are associated with cataract.

Exploring the Occurrence Mechanisms of Acute Primary Angle Closure by Comparative Analysis of Ultrasound Biomicroscopic Data of the Attack and Fellow Eyes.

PURPOSE: To explore the anatomical characteristics and occurrence mechanisms of acute primary angle closure (APAC) by comparing the quantitative data of UBM images of the APAC and fellow eyes. METHODS: 131 patients (262 eyes) were studied over five years by retrospective analysis. The quantitative data from UBM images including angle opening distance at 500 µm (AOD500), trabecular-iris angle (TIA), iris convexity (IC), iris span (IS), iris-lens angle (ILA), iris-lens contact distance (ILCD), iris-ciliary process angle (ICPA), and limbus-ciliary body angle (LCBA) were retrospectively recorded; comparative analysis of the APAC and fellow eyes was performed. RESULTS: The superior, inferior, nasal, temporal, and mean AOD500, TIA, IC, and LCBA (P < 0.001) were significantly smaller in APAC than in fellow eyes. Values of the lens thickness (LT), lens/axial length factor (LAF), lens position (LP), and relative lens position (RLP) were lower in APAC than in fellow eyes (P = 0.021; P = 0.025; P < 0.001; and P < 0.001). In APAC eyes, AOD500 was significantly positively correlated with IC, ILCD, and LCBA; TIA was significantly positively significantly correlated with IC, ILCD, and LCBA. In fellow eyes, AOD500 was significantly negatively correlated with ILA and significantly positively correlated with ILCD, ICPA, LCBA, axial length (AL), central anterior chamber depth (CACD), and LP; TIA was significantly negatively correlated with ILA and significantly positively correlated with IS, ILCD, ICPA, LCBA, AL, CACD, LP, and RLP. CONCLUSIONS: Multiple nonpupillary block factors (plateau iris, anterior attachment and insertion of the iris root, anterior shift of the lens, and anterior rotation of the ciliary body) promote the occurrence of APAC, and abnormal positional relationships of the iris, ciliary body, and lens may contribute to APAC.

Crystalline lens gradient refractive index distribution in the guinea pig.

PURPOSE: The crystalline lens undergoes morphological and functional changes with age and may also play a role in eye emmetropisation. Both the geometry and the gradient index of refraction (GRIN) distribution contribute to the lens optical properties. We studied the lens GRIN in the guinea pig, a common animal model to study myopia. METHODS: Lenses were extracted from guinea pigs (Cavia porcellus) at 18 days of age (n = 4, three monolaterally treated with negative lenses and one untreated) and 39 days of age (n = 4, all untreated). Treated eyes were myopic (-2.07 D on average) and untreated eyes hyperopic (+3.3 D), as revealed using streak retinoscopy in the live and cyclopeged animals. A custom 3D spectral domain optical coherence tomography (OCT) system (λ = 840 nm, Δλ = 50 nm) was used to image the enucleated crystalline lens at two orientations. Custom algorithms were used to estimate the lens shape and GRIN was modelled with four variables that were reconstructed using the OCT data and a minimisation algorithm. Ray tracing was used to calculate the optical power and spherical aberration assuming a homogeneous refractive index or the estimated GRIN. RESULTS: Guinea pig lenses exhibited nearly parabolic GRIN profiles. When comparing the two age groups (18- and 39 day-old) there was a significant increase in the central thickness (from 3.61 to 3.74 mm), and in the refractive index of the surface (from 1.362 to 1.366) and the nucleus (from 1.443 to 1.454). The presence of GRIN shifted the spherical aberration (-4.1 µm on average) of the lens towards negative values. CONCLUSIONS: The guinea pig lens exhibits a GRIN profile with surface and nucleus refractive indices that increase slightly during the first days of life. GRIN plays a major role in the lens optical properties and should be incorporated into computational guinea pig eye models to study emmetropisation, myopia development and ageing.

Cataract Formation and Low-Dose Radiation Exposure from Head Computed Tomography (CT) Scans in Ontario, Canada, 1994-2015.

Ionizing radiation exposure to the lens of the eye is a known cause of cataractogenesis. Administrative data from the Ontario Health Insurance Program was used to examine the association between low-dose radiation exposure from head CT scans and cataract extraction surgery for 16 million Ontarians over a 22-year period (1994-2015). Subjects were grouped based on the number of head CT scans they received, and a Cox proportional hazards analysis was used to determine if there was a correlation with cataract surgery. Covariates included in the analysis were age, sex, diabetes, hypertension and prior history of intraocular surgery. To account for the potentially long latency period between radiation exposure and cataract formation, the data were analyzed incorporating a 5- and 10-year lag between head CT scan exposure and cataract surgery. Both the 5- and 10-year lagged models followed a similar trend, where only the first three head CT scans significantly increased the risk of cataract surgery by 3-8%. Individuals receiving four or more head CT scans did not have an increased cataract risk and in several cases the risk was reduced. Overall, no positive dose-response relationship was seen between the number of head CT scans received and the risk of cataract surgery. Due to the nature of the data extracted from medical records, several uncertainties exist in the analysis related to dosimetry, ultraviolet light exposure and smoking status. Nonetheless, these results do not support an association between ionizing radiation from repeated head CT scans and cataract formation.

Effectiveness of intraoperative intraocular lens use on improving surgical safety for dense cataract phacoemulsification: a randomized controlled trial.

We designed this study to assess if surgical safety can be improved by intraoperative use of intraocular lens (IOL) for cataract phacoemulsification. We performed phacoemulsification cataract removal on 401 patients. We randomly assigned these patients into three groups: the standard setting (Group I, n = 134), with reduced vacuum and flow rate (Group II, n = 137), and with IOL insertion before the last quadrant was emulsified with standard setting (Group III, n = 130). The primary outcomes included the risk of posterior capsular rupture (PCR), ultrasound time, energy, and complications. The secondary outcomes included central corneal thickness (CCT), CCT changes, endothelial cells (ETC) counting, ETC loss, and the best corrected distance visual acuity (BCVA) measured on day 1, day 7 and day 30. If PCR occurred, we emulsified the residual lens materials after insertion of IOL and clean of the prolapsed vitreous. We found that the risk of PCR in Group III (0/130) was lower than Group I (9/134, corrected relative risk (RR) = 18.44, 95% CI: 1.08-313.56) and Group II (3/137, corrected RR = 6.64, 95% CI: 0.35-27.41). Group III showed better BCVA on day 1 and 7, less ECC loss on day 7 and 30, and less CCT increase on day 1 and 7. No cases converted to extracapsular cataract extraction. No residual lens materials misdirected into vitreous cavity. Intraoperative use of IOL can improve surgical safety for dense cataract phacoemulsification.

Changes in forward light scatter parameters as a function of refractive error in young adults.

BACKGROUND/AIMS: Some aspects of visual performance worsen with increasing myopia. Whilst the underlying causes are not always clear, reduction in retinal image quality is often attributed to structural changes in the posterior myopic eye. Forward light scatter, originating principally from the cornea and lens, is known to produce veiling glare which subsequently reduces retinal image contrast. It is therefore of interest to investigate whether forward light scatter varies with refractive error. METHODS: Thirteen young-adult subjects (18-25 years), with mean spherical errors (MSE ± sd, D) RE, - 1.69 ± 2.02 (range 0.38 to - 4.75); LE, - 1.91 ± 1.94 (range 0.50 to - 4.63) underwent binocular assessment of forward light scatter using the AVOT light scatter test. Five glare annuli, with effective eccentricities ranging from 2 to 10°, were used to estimate parameters, k and n, which define the light scatter function of the eye. These were then used to calculate the area under the light scatter function (k') and the total volume of light scatter (k″). RESULTS: Significant correlation was found between increasing myopia and k' values (RE, p < 0.05; r = 0.64; LE, p < 0.05, r = 0.66). Neither the 'volume' of light scatter (k″), the parameter, n, which controls the angular distribution of light scatter, or the straylight parameter constant, k, were significantly correlated with refractive error (p > 0.05 for both eyes). Axial length was also not correlated with any of the light scatter parameters measured. CONCLUSION: The preliminary data from this study provide evidence that some light scatter parameters may be correlated with refractive error. Further studies are needed to characterize how changes in the anterior media of the eye, and inclusion of a wider range of refractive errors, may affect forward light scatter.

Cataract surgery reduces intraocular pressure but not posture-induced intraocular pressure changes in patients with angle-closure glaucoma.

Cataract surgery leads to a sustained decrease in sitting intraocular pressure (IOP) in patients with angle-closure glaucoma (ACG). The purpose of this study is to evaluate whether cataract surgery can also reduce postural IOP changes. We prospectively examined 106 eyes from 53 patients with narrow angles scheduled for phacoemulsification. IOP was measured in the sitting, supine, and lateral decubitus positions using an ICare rebound tonometer before and 1 week, 1 month, and 3 months postoperatively. The mean baseline IOP in the sitting and lateral decubitus positions was 17.9 ± 4.8 mmHg and 21.43 ± 6.44 mmHg, which significantly reduced to 13.52 ± 3.8 and 17.46 ± 3.62, respectively, 3 month postoperatively (p < 0.001). However, postural IOP change (lateral decubitus minus sitting) at 3 months postoperatively was not significantly different from that at the baseline (3.17 ± 2.63 vs. 3.53 ± 3.38 mmHg, p = 0.85). Postural IOP change was not associated with preoperative sitting IOP, anterior chamber depth, axial length, fixed pupil, or presence of glaucomatous optic neuropathy. Patients with higher preoperative IOP exhibited greater IOP reduction after cataract surgery in every posture (p < 0.0001). In conclusion, cataract surgery reduces IOP in all postures among patients with ACG; however, it does not reduce the magnitude of postural IOP change.

Distribution of corneal spherical aberration in a Tanzanian population.

PURPOSE: To investigate the distribution of corneal spherical aberration (SA) in Tanzanian people of African descent, and to examine the correlation between corneal SA and ocular parameters. DESIGN: Cross-sectional population-based study. METHODS: Residents aged 40 years and older in three villages in the Mkuranga district in Tanzania were enlisted as study participants. Corneal higher-order aberrations (HOAs) for the right eye were measured with a wavefront analyzer (KR-1W, Topcon) and calculated for the central 6.0-mm zone. Corneal curvature radius (CR), corneal astigmatism, and axial length (AL) were also measured and their correlation with corneal SA was assessed. RESULTS: The right eyes of 657 participants (336 male, 321 female) were analyzed. The mean age of the subjects was 57.2 ± 10.3 years (mean ± SD). The mean corneal SA (Zernike spherical aberration coefficient C40) was 0.188 ± 0.095 µm (-0.242 to 0.613). The SAs in about three-quarters of all subjects were between 0.10 and 0.30 µm. The root mean squares of total corneal HOAs and the third- and fourth-order aberrations were 0.629 ± 0.250 µm, 0.539 ± 0.236 µm, and 0.269 ± 0.110 µm, respectively. Corneal SA showed weak significant correlations with CR (Spearman's rank correlation coefficient, r = -0.177, p < 0.001), corneal astigmatism (r = -0.142, p < 0.001), AL (r = -0.168, p < 0.001), and age (r = -0.085, p < 0.05). CONCLUSIONS: This finding may be beneficial for selecting aspheric intraocular lens in this population.

Visual Function and Functional Decline in Patients With Waterclefts.

Purpose: To investigate visual function in eyes with three subtypes of waterclefts (WCs). Methods: Of patients in Kanazawa Medical University Hospital (2013-2017) and participants of Monzen Eye Study (2013-2016), 77 transparent lenses, mean age 66.7 years, and 70 eyes with only WC opacity of 70 patients, mean age 68.1 years, divided into peripheral-, central-, and total-type WC groups, were analyzed. Opacity was classified by one ophthalmologist using slit-lamp microscopy. Corrected-distance visual acuity (CDVA), contrast visual acuity (CVA), spherical equivalent (SE), astigmatism values, corneal refractive power (CP), axial length (AL), straylight, backward light scattering (BLS), and higher order aberrations (HOA) were measured and lenticular refractive power (LP) was calculated based on the values of AL, CP, and SE. Results: Central-type WC showed significant decrease in CDVA and CVA and increase in straylight compared with control. Total-type WC showed significant decreases in CDVA, CVA, and LP, and increase in straylight, compared with control and peripheral-type WC. Total- and central-type WCs had significantly higher ocular total HOA and total-type WC had significantly higher internal total HOA than control. HOA correlated positively with CDVA (P < 0.001) and straylight (P = 0.020), and CDVA negatively with straylight in eyes with WCs (P = 0.008). Conclusions: Total-type WC was associated with decreased LP, causing hyperopia, decreased CDVA and higher straylight; thus, such lenticular change should be considered for surgery indication. Significant correlations between HOA and both CDVA and straylight suggested increased HOA may decrease visual function in eyes with WCs.

An objective scatter index cutoff point as a powerful objective criterion for preoperative nuclear cataract decision-making based on ROC analysis.

PURPOSE: To assess the correlation between clinical cataract surgery indication and the objective scatter index (OSI) by defining the optimal OSI cutoff point in the surgery scheduling. SETTING: Ophthalmology service, Consorcio Hospital General Universitario, Valencia, Spain. DESIGN: Prospective triple-masked randomized single-center study. METHODS: Patients with cataractous eyes were recruited, and those with anterior segment disease, abnormal posterior pole, and/or previous ocular surgery were excluded. The principle of double-pass aberrometry was used by the main investigator to determine an OSI, after measuring subjective refraction and corrected distance visual acuity (CDVA), and then slitlamp evaluation was carried out by an independent researcher. The surgical decision was based on the current protocol according to the European guidelines. Correlation between the surgical decision, CDVA, and OSI were analyzed and an OSI discriminative value was calculated, implementing a receiver operating characteristic (ROC) curve. RESULTS: The study comprised 106 eyes (73 patients). The analysis established an inverse linear correlation between OSI and CDVA (r = -0.455, P < .0001). The comparison of the mean OSI between the surgical group (7.05 ± 4.65 [SD]) and the nonsurgical group (2.92 ± 1.88), revealed statistically significant differences (P = 5.04 × 10-9). The OSI score 3.2 was determined as the optimal cutoff value to discriminate surgical treatment (sensitivity 80%, specificity 84%). CONCLUSIONS: An optimal OSI value, according to an ROC curve calculation, was capable of providing clinicians with a powerful criterion for preoperative decision-making, thus suggesting an end to the subjectivity implicit in the cataract surgery decision-making process.

Phacoemulsification Cataract Surgery Affects the Discriminative Capacity of Iris Pattern Recognition.

Cataract is a common ophthalmic disorder and the leading cause of blindness worldwide. While cataract is cured via surgical procedures, its impact on iris based biometric recognition has not been effectively studied. The key objective of this research is to assess the effect of cataract surgery on the iris texture pattern as a means of personal authentication. We prepare and release the IIITD Cataract Surgery Database (CaSD) captured from 132 cataract patients using three commercial iris sensors. A non-comparative non-randomized cohort study is performed on the iris texture patterns in CaSD and authentication performance is studied using three biometric recognition systems. Performance is lower when matching pre-operative images to post-operative images (74.69 ± 9.77%) as compared to matching pre-operative images to pre-operative images (93.42 ± 1.76%). 100% recognition performance is observed on a control-group of healthy irises from 68 subjects. Authentication performance improves if cataract affected subjects are re-enrolled in the system, though re-enrollment does not ensure performance at par with pre-operative scenarios (86.67 ± 5.64%). The results indicate that cataract surgery affects the discriminative nature of the iris texture pattern. This finding raises concerns about the reliability of iris-based biometric recognition systems in the context of subjects undergoing cataract surgery.